Problem when importing .obj to Blender
There are Custom Split Normals creating artifacts in your mesh.
Go to Properties Window &gt; Object Data Tab &gt; Geometry Data Panel and press Clear Custom Split Normals Data
If for some reason you wish to keep those, disabling Auto Smooth under the Properties Window &gt; Object Data Tab &gt; Normals Panel &gt; Auto Smooth seems to be a valid workaround.
Also, if you horse is to remain perfectly symmetric consider erasing half of the mesh and adding a Mirror modifier. Might save you some cleanup work and resources in the future.